CrossFit was founded by gymnast Greg Glassman (with Laura Classman) in 2000.
Preparing the body “not only for the known, but also the unknown” is the mantra for CrossFit, one of the fastest growing strength and conditioning programs today. It is not a traditional, specialized training program like doing isolated weight lifting for a certain muscle or aerobics. Source
In other words their specialty is not specializing. This is not the workout for you if you are a novice. It is tough.
CrossFit combines strength training, explosive plyometrics (exercises based around having muscles exert maximum force in as short a time as possible), speed training, Olympic- and power-style weight lifting, kettle bells, body weight exercises, gymnastics, and endurance exercises.
CrossFit targets what it calls the major components of physical fitness: cardiorespiratory fitness, stamina, muscular strength and endurance, flexibility, power, speed, agility, balance, coordination, and accuracy.
You will be working out three to five day a week and considered HIT (high intensity training). The workouts only take about five to fifteen minutes to complete.
They are done in a circuit form (one right after the other) with very little if any rest. You will be working your entire body – rowing, squatting, running, etc.
CrossFit posts a Workout of the Day (WOD) on its web site. Some of the WOD are named after women or military heroes. One example is The Barbara, which involves five circuits of 20 pull-ups, 30 push-ups, 40 sit-ups, and 50 body weight-only squats performed in order, while only resting at the end of each circuit for a 3-minute period.
Other exercises include:
Beginning in a handstand, with the arms straight and (usually) the heels gently resting against a wall, the athlete bends the arms until the head touches the ground, and then pushes back up into a handstand position.
The most common variation in CrossFit is the "double under" in which the jump rope makes two revolutions for each jump.
A kettlebell is swung from between the legs to overhead.
A barbell is raised from the floor to the overhead position in one motion. In a squat snatch the athlete receives the bar in a squatting position and stands to finish the lift. In a power snatch, the athlete receives the bar in a partial squat.
The barbell is supported on upper back (back squat), in the rack position (front squat), or in the overhead position (overhead squat). From a standing position with a wider-than-shoulder-width stance, the athlete bends the knees until the hips are below the knees, and then stands, keeping the heels on the floor.